On Fri, 18 Jan 2002, Hans Otten wrote: > I did not check the address line logic in your diagram, it seems allright. > All necessary lines are covered (slot select and CSx are most important) and > kept high. Addresslines above A7 are therefore irrelevant, since the inernal > rom will stay disabled.
Thanks, Hans. I've made a clearer version of the schematic, which is functionally identical: http://student.cusu.cam.ac.uk/~rga24/computer/projects/adaptor-simplified.pdf I tied spare lines high to keep CMOS input buffers happy, although my Zemina uses even fewer lines than I have connected. Hopefully this will be compatible with other MSX-MUSICs out there. Curiously, my Zemina doesn't use A14 even though it has a 27256 ROM. Could it be using just half of the chip? > If the clock is equivalent to MSX then it is doable this way! > > What is I/O address F2 used for anyway? It is now just a r/w store? No one seems to know what actual hardware is inside the Japanese Sega Master System or Mark III FM expander, but the software routines check that this location can store bits. There are other questions too, which will be answered when someone finally takes a Japanese SMS apart. Richard -- For info, see http://www.stack.nl/~wynke/MSX/listinfo.html
